Mail Management Improvement Act of 1986 - Requires the Director of the Office of Management and Budget, in consultation with the Administrator of General Services, within 90 days of enactment of this Act, to issue a directive which requires each agency to: (1) evaluate mail operations to eliminate practices resulting in excessive mailing costs; (2) designate an official with the responsibility for the development and implementation of mail management programs; (3) establish mail management objectives and responsibilities; and (4) develop and submit to the Director a mail management plan in accordance with provisions of this Act.